Pouch-type secondary battery including sealed part having recess

Abstract

Disclosed herein is a battery cell configured such that an electrode assembly having a positive electrode/separator/negative electrode structure is received in an electrode assembly receiving part formed in a pouch-type battery case in a sealed state together with an electrolyte, wherein the battery case is provided with sealed parts, formed by thermally welding the outer edge of the battery case in the state in which the electrode assembly is received in the battery case together with the electrolyte, one or more recesses are formed in opposite side sealed parts adjacent to an upper end sealed part, at which electrode terminals are located, and/or a lower end sealed part in a state in which the recesses are formed from outsides of the side sealed parts toward a vertical middle axis of the battery cell so as to prevent wrinkles from being formed in the sealed parts of the battery case when the battery cell is bent, and portions of the side sealed parts in which the recesses are located are sealed at a higher sealing temperature than the remaining portions of the side sealed parts.

The invention claimed is: 
     
       1. A battery cell configured such that an electrode assembly having a positive electrode/separator/negative electrode structure is received in an electrode assembly receiving part formed in a pouch-type battery case in a sealed state together with an electrolyte, wherein
 the battery case is provided with sealed parts, formed by thermally welding an outer edge of the battery case in a state in which the electrode assembly is received in the battery case together with the electrolyte, 
 one or more recesses are formed in opposite side sealed parts adjacent to an upper end sealed part, at which electrode terminals are located, and/or a lower end sealed part in a state in which the recesses are formed from outsides of the side sealed parts toward a vertical middle axis of the battery cell so as to prevent wrinkles from being formed in the sealed parts of the battery case when the battery cell is bent, 
 one or more recesses are formed in portions of an outer surface of the electrode assembly that face the recesses formed in the side sealed parts, the one or more recesses formed in portions of the outer surface of the electrode assembly having the same shape as the recesses formed in the side sealed parts, and 
 portions of the side sealed parts in which the recesses are located are sealed at a higher sealing temperature than the remaining portions of the side sealed parts so that portions of the side sealed parts in which the recesses are formed have a higher coupling strength than the remaining portions of the side sealed parts. 
 
     
     
       2. The battery cell according to  claim 1 , wherein the battery case is made of a laminate sheet comprising a resin layer, a metal layer, and a sealant layer. 
     
     
       3. The battery cell according to  claim 1 , wherein the electrode terminals comprise a positive electrode terminal and a negative electrode terminal, which are located on the upper end sealed part. 
     
     
       4. The battery cell according to  claim 1 , wherein a positive electrode terminal, which is one of the electrode terminals, is located on the upper end sealed part, and a negative electrode terminal, which is the other of the electrode terminals, is located on the lower end sealed part. 
     
     
       5. The battery cell according to  claim 1 , wherein the battery cell is bent about the recesses, formed in the sealed parts. 
     
     
       6. The battery cell according to  claim 1 , wherein two or more recesses are formed in each of the opposite side sealed parts. 
     
     
       7. The battery cell according to  claim 1 , wherein the same numbers of recesses are formed in the opposite side sealed parts. 
     
     
       8. The battery cell according to  claim 1 , wherein the recesses are formed in portions of the side sealed parts located on a horizontal axis extending through a middle of the electrode assembly receiving part. 
     
     
       9. The battery cell according to  claim 1 , wherein the recesses are formed in portions of the side sealed parts spaced apart from a horizontal axis extending through a middle of the electrode assembly receiving part. 
     
     
       10. The battery cell according to  claim 9 , wherein the recesses are formed in portions of the opposite side sealed parts spaced apart from the horizontal axis by the same distance or different distances. 
     
     
       11. The battery cell according to  claim 1 , wherein each of the recesses has a polygonal or arc planar structure. 
     
     
       12. The battery cell according to  claim 1 , wherein the recesses are formed in the sealed parts such that each of the recesses has a depth (a) equivalent to 0.2 to 0.8 times a width (W) of a corresponding one of the sealed parts. 
     
     
       13. The battery cell according to  claim 1 , wherein the recesses are formed in the sealed parts such that each of the recesses has a width (b) equivalent to 0.1 to 2 times a width (W) of a corresponding one of the sealed parts. 
     
     
       14. The battery cell according to  claim 1 , wherein two or more recesses are successively arranged along at least one of the opposite side sealed parts in a state in which the recesses are adjacent to each other. 
     
     
       15. The battery cell according to  claim 1 , wherein the portions of the side sealed parts in which the recesses are located are thermally welded at a thermal welding temperature 5° C. to 30° C. higher than the remaining portions of the side sealed parts. 
     
     
       16. The battery cell according to  claim 15 , wherein the portions of the side sealed parts in which the recesses are located are thermally welded at a thermal welding temperature 10° C. to 20° C. higher than the remaining portions of the side sealed parts. 
     
     
       17. The battery cell according to  claim 15 , wherein the remaining portions of the side sealed parts are thermally welded at a thermal welding temperature of 160° C. to 200° C. 
     
     
       18. The battery cell according to  claim 17 , wherein the remaining portions of the side sealed parts are thermally welded at a thermal welding temperature of 170° C. to 195° C. 
     
     
       19. A method of manufacturing a battery cell according to  claim 1 , the method comprising:
 (a) thermally welding portions of an outer edge of a battery case, excluding one end of the outer edge of the battery case, to seal the remaining portions of the outer edge of the battery case in a state in which an electrode assembly is mounted in an electrode assembly receiving part formed in the battery case; 
 (b) injecting an electrolyte through the one end of the outer edge of the battery case, which has not been sealed, and thermally welding the one end of the outer edge of the battery case; and 
 (c) forming recesses in opposite side sealed parts from outsides of the opposite side sealed parts toward a vertical middle axis of the battery cell. 
 
     
     
       20. A method of manufacturing a battery cell according to  claim 1 , the method comprising:
 (a) forming recesses in opposite side sealed parts from outsides of the opposite side sealed parts toward a vertical middle axis of the battery cell in a state in which an electrode assembly is mounted in an electrode assembly receiving part formed in a battery case; 
 (b) thermally welding portions of an outer edge of the battery case, excluding one end of the outer edge of the battery case, to seal the remaining portions of the outer edge of the battery case; and 
 (c) injecting an electrolyte through the one end of the outer edge of the battery case, which has not been sealed, and thermally welding the one end of the outer edge of the battery case.